1. Field of the Invention
The present invention relates to an apparatus for extracorporeal circulation of blood. More particularly, the invention is directed to an apparatus including an extracorporeal blood circuit having at least one chamber for containing liquid in its lower portion and air in its upper portion. The chamber is connected to a pump for causing the quantity of air to vary in the chamber.
2. Description of the Related Art
In the related art, similar devices are known which are particularly useful for treating blood by dialysis. U.S. Pat. No. describes an extracorporeal blood circuit having an arterial portion for conveying the blood of a patient to a haemodialyser, and a venous portion for returning the treated blood to the patient. Each of the arterial and venous portions includes a chamber with an upper portion connected to a pump, for adjusting the level of the liquid in the chamber by the addition or withdrawal of air. However, the operation of the pump is controlled manually according to the level of the liquid observed visually by the operator.
This visual monitoring represents a considerable constraint as far as the user is concerned, who is unable to monitor the liquid level a permanent basis. Indeed, in a treatment center such as a dialysis center, a single nurse is in charge of supervising several stations, and she must therefore supervise the proper operation of several machines, as well as the health conditions of the patients at the same time. However, maintaining the level of the liquid in the chamber is essential for an efficient and reliable treatment. It is, on the one hand, necessary to avoid spillovers of the blood and on the other hand, necessary to maintain a minimum level of liquid in the chamber. An undue fall in the liquid level in a chamber situated in the arterial portion could lead to air being introduced into the haemodialyser, which would greatly reduce its efficiency, while a fall in the liquid level in a venous chamber could lead to air being introduced into the patient's blood system, which could have serious consequences. It is therefore important to ensure proper monitoring and correction of the liquid level in the chambers on a permanent basis, without any constraints on the user and with a high degree of safety.